I. Technical Field
This disclosure generally relates to a high strength titanium alloy and techniques for manufacture of the same. The alloy is advantageously used for applications wherein high strength, deep hardenability, and excellent ductility are a required combination of properties.
II. Background of the Related Art
Conventionally, various titanium and steel alloys have been used for the production of aviation components. The use of titanium alloys is favorable since it results in lighter components than those made from steel alloys.
An example of such a titanium alloy is disclosed in U.S. Pat. No. 7,332,043 (“the '043 patent”) to Tetyukhin, et al. which describes use of a Ti-555-3 alloy composed of 5% aluminum, 5% molybdenum, 5% vanadium, 3% chromium, and 0.4% iron in aeronautical engineering applications. However, the Ti-555-3 alloy does not consistently provide the desired high strength, deep hardenability, and excellent ductility required for critical applications in the aviation industry (e.g., landing gear). Moreover, the '043 patent fails to disclose the use of oxygen in its Ti-555-3 alloy, an important element in the composition of titanium alloys. The oxygen percentage is often purposefully adjusted to have a significant impact on strength characteristics.
Another example is provided in U.S. Patent Application Publication No. 2008/0011395 (hereinafter “the '395 application”) which describes a titanium alloy which includes aluminum, molybdenum, vanadium, chromium, and iron. However, the weight percentage ranges for the elements of the alloy provided in the publication are overly broad. For example, the alloys Ti-5Al-4.5V-2Mo-1Cr-0.6Fe (VT23) and Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) readily fall within the specified weight percentage ranges. These alloys have been in the public domain dating back to before 1976. Additionally, the preferred ranges of weight percentages provided in the '395 application result in poor strength-ductility combinations. Therefore, the reference does not achieve the desired high strength, deep hardenability, and excellent ductility required for critical applications in the aviation industry such as landing gear.
There therefore is a need for an alloy with improved strength, deep hardenability, and excellent ductility characteristics to meet the needs of critical applications in the aviation industry. The crucial properties for such a product are high tensile strengths (e.g., tensile yield strength (“TYS”) and ultimate tensile strength (“UTS”)), modulus of elasticity, elongation, and reduction in area (“RA”). Moreover, there is a need for advanced techniques for manufacturing and processing such an alloy to further improve its performance.